The present invention relates to methods for producing chewing gum. More particularly, the invention relates to methods for producing chewing gum containing acetals of benzaldehyde and peptide sweeteners with improved shelf-life stability.
In recent years, efforts have been devoted to protecting peptide sweeteners within the chewing gum formulation from interaction in the presence of aldehyde ingredients, i.e., the protection of the high-potency sweetener against degradation over time. The instability is significant because aldehyde-containing flavor components have been known to react with peptide sweeteners such as aspartame and thereby greatly reduce the shelf-stability of aspartame in such a gum.
For example, U.S. Pat. Nos. 4,722,845, issued Feb. 2, 1988, and 4,839,184, issued Jun. 13, 1989, both to Cherukuri et al., teach a process for stabilizing an aldehyde-containing chewing gum in which a dipeptide or amino acid sweetener is encapsulated in a mixture of fat, wax and glyceride. The inventions teach an advantage in using an edible wax with a melting point of 106.degree. C. or greater. First, the fat, wax and glyceride are mixed to form a "hydrophobic matrix." Then, the sweetener is formed into an agglomerate with this hydrophobic matrix. The agglomerates are next screened for appropriate size. Finally, the second or further coating with the hydrophobic matrix is applied using standard fluidized bed granulation techniques. Alternately, the initial coating can be applied by spray congealing techniques. Both of the above Cherukuri et al. patents teach that aspartame is difficult to coat, because of its needle-like shape. To adequately coat aspartame, approximately six times as much coating material as aspartame was used.
U.S. Pat. No. 4,863,745, issued Sep. 5, 1989, to Zibell, teaches a method of encapsulating aspartame or other high-potency sweeteners by applying to already-coated aspartame a second coat consisting predominately of zein, a corn protein. This method results in more gradual release of high-potency sweetness and in protection from degradation by aldehyde constituents.
U.S. Pat. No. 4,931,295, issued Jun. 5, 1990, to Courtright et al., discloses the preparation of a softer zein coating for aspartame which is water soluble and includes water-soluble cellulose. Courtright et al. disclose that encapsulation and protection from degradation occurs when the final product comprises as little as 10% zein.
Examples of aldehyde containing flavoring agents include, but are not limited to, cinnamon flavor, which includes cinnamaldehyde; cherry flavor, which includes benzaldehyde; lemon flavors, which contain citral and citronellal; vanilla flavor, which includes vanillin and ethyl vanillin; fruit flavors, which include acetaldehyde; and orange flavor, which includes undecanal. Other flavors which include aldehyde-containing components can be found on pages 325-328 of the book Flavor Technology: Profiles, Products, Applications, by Henry B. Heath, M.B.E., B. Pharm., published in 1978 by The AVI Publishing Co., Inc., Westport, Conn. Cherry flavor is a popular aldehyde-containing flavor used in chewing gum and includes benzaldehyde.
Benzaldehyde is the primary ingredient in cherry flavoring. In Section 268 of Volume 1 of Steffen Arctander's Perfume and Flavor Chemicals, published by the author in Montclair, N.J. in 1969, benzaldehyde is described as having a "powerful sweet odor, reminiscent of freshly crushed bitter almonds." Besides cherry and almond, benzaldehyde is used in "berry, butter, apricot, brandy, coconut, liquor, peach, plum, pecan, pistachio, rum spice and vanilla." Id. Benzaldehyde has been added to a variety of foods, including gum. In chewing gum, however, the benzaldehyde flavor reacts with peptide sweeteners where present to form non-sweet products. In addition, the cherry flavor may change after a few minutes of chewing. Methods of preventing the dissipation of aldehyde flavors, including the chemical combination of aldehyde flavors with other moieties, have been investigated.
Co-pending, commonly assigned, U.S. patent application Ser. No. 07/577,770, filed on Sep. 4, 1990, by Michael Greenberg and Sonya Johnson, entitled "Method of Stabilizing Peptide Sweeteners in Cinnamon-Flavored Chewing Gums and Confections," discloses the combination of dipeptide sweeteners and cinnamaldehyde acetal, and particularly cinnamaldehyde propylene glycol acetal (CAPGA), in gum and other foods. The acetals of benzaldehyde also have been reported.
In Section 274 of Arctander's Perfume and Flavor Chemicals, benzaldehyde propylene glycol acetal is described as useful "in flavor compositions for imitation cherry, almond, nut, etc. particularly where greater stability and lower volatility . . . is desirable." Arctander also notes that "the acetal itself is practically odorless but will liberate benzaldehyde under influence[s] of moisture (particularly in the presence of acid) and heat." Id.
In Section 272 of Arctander's Perfume and Flavor Chemicals, benzaldehyde ethylene glycol acetal is described as "almost odorless when free from benzaldehyde but traces of moisture will free some aldehyde and influence the odor," suitable for "compositions where storage conditions favor a more stable form of benzaldehyde." Arctander points out that "the aldehyde is liberated under [the] influence of water, heat or acid." Id.
In Section 269 of Arctander's Perfume and Flavor Chemicals, benzaldehyde diethyl acetal is described as having a sweet, mild flavor, "faintly reminiscent of . . . bitter almond, but more herbaceous." Arctander notes that this acetal "offers some advantage in being milder, easier to handle, but . . . this material is sensitive to mild acid." Id.
In Section 273 of Arctander's Perfume and Flavor Chemicals, benzaldehyde glyceryl acetal is described as having a faint bitter almond odor and being a mixture of two acetals, a 1,2-form and a 1,3-form. This acetal is "used in flavor compositions where lower volatility and improved stability towards air (oxygen) is desirable, and the benzaldehyde as such seems too volatile and unstable." Id. "Under the influence of heat, water or mild acid," "the acetal will liberate benzaldehyde." Id. This acetal is "used in fruit flavors, imitation almond, cherry [and] nut," and "the most common outlet for the acetal" is chewing gum. Id.
In Section 271 of Arctander's Perfume and Flavor Chemicals, benzaldehyde dimethyl acetal is described as having a "sweet-green and warm odor, remotely reminiscent of nuts and bitter almonds" and is "used in . . . cherry, fruit, nut, [and] almond" flavors. This acetal also is "sensitive to mild acid and will not be stable in finished products of low pH." Id.
In Section 270 of Arctander's Perfume and Flavor Chemicals, benzaldehyde di-(ethylene glycol monobutyl ether) acetal is described as having a "mild-herbaceous, sweet and floral odor" and being used in jasmine fragrance.
Acetals have been combined with other flavor chemicals to produce longer-lived chemicals. U.S. Pat. No. 3,898,283, issued Aug. 5, 1975, to Schreiber et al., teaches methods to produce phenyl pentenals, as well as their acetals.
U.S. Pat. No. 3,908,023, issued Sep. 23, 1975, to Schreiber et al., further teaches the production of cinnamon like flavors with phenyl pentenals and their acetals. However, Schreiber points out that these chemicals are very stable, only hydrolyzing under "intense hydrolytic conditions" (col. 2, line 66). These conditions include a pH which is less than 2.5 or greater than 11.5, far different from the relatively neutral pH of saliva. This reference also teaches that 1,2- and 1,3-propylene glycol may be used in acetals to stabilize phenyl pentenals (col. 6, line 13).
U.S. Pat. No. 3,879,425, issued Apr. 22, 1975, to Hall et al., teaches that 3-phenyl-4-pentenal ethylene acetal is a stable precursor for the aldehyde, which has a green floral fragrance. It teaches that a variety of phenyl pentenals, can be combined with a variety of acetals. A list of such acetals includes propylene glycol acetal (col. 9, lines 50-51).
U.S. Pat. No. 4,571,344, issued Feb. 18, 1986, to Pittet et al., teaches preparation of a sustained release flavor by combining dithioethers of phenyl alkenals with silica and propylene glycol (cols. 23 and 24). Pittet also teaches using the silica mixture in chewing gum (col. 24, lines 43-54). Pittet also reports long-lasting flavor with the dithioether flavor alone (col. 24, lines 58-64).
Unfortunately, a disadvantage of all techniques for preventing peptide sweeteners from interacting with aldehyde compounds is that they call for encapsulating the sweetener. The more effective techniques for encapsulating the sweetener require long drying periods and coating the sweetener at least twice, an expensive process. Even then, the peptide sweetener is not always fully protected. What is needed is less expensive and more convenient protection of peptide sweeteners from chemical degradation by aldehyde compounds.